Analysis Of Seismic Response Of Long Span Cable-Stayed Bridge

Because of its unique structure, cable-stayed bridge won the spanning capacity far more than beam bridge. Compared to suspension bridge, cable-stayed bridge has many advantages:no requirement to expensive ground anchors as a self-anchored system; lower technical requirements for corrosion; greater stiffness for wind resistance; cantilever construction method can be used, causing no navigable trouble and less requirements to prestressed tendons. Thus, cable-stayed bridge has become one of the most mainstream bridge types of long-span bridges.As a multi-earthquake country, long-span cable-stayed bridge is commonly constructed as the lifeline of our country. So once bridge suffered earthquake, huge loss is following, and secondary disasters will be caused by inefficient relief work. So seismic analysis of long-span cable-stayed bridge is very important.In this thesis, the main research is as follows:(1) The principle, advantages and disadvantages of seismic analysis methods of bridge:static analysis method, response spectrum method and time-history analysis method are discussed.(2) Based on the background, the finite element model of Fengdu Yangtze River Bridge is established. Considering pile-soil-structure interaction or not, the analysis of both model are calculated for dynamic characteristics. Through comparison:while considering pile-soil-structure interaction, vibration frequency is smaller and the order of vibration mode changes.(3) Conclusions based on spectrum response analysis are obtained:the single direction seismic input only causes structure response in the seismic direction; while considering pile-soil-structure interaction, the displacement response of the structure increases; inter force response of the beam increases; bending moment of the main tower is reduced; axial force and shear increases.(4) The amplitude, period and duration of the EI-centro seismic wave, is adjusted as the seismic input. The conclusion of time-response analysis method is compared to that of response spectrum method. The result of time-response analysis method is no less than80% of the result of response spectrum method.(5) In order to study the effect of traveling wave on the seismic response, five seismic waves with different phase difference are used as the seismic input. Compared to the uniform excitation, while considering traveling wave effect, the displacement of the tower and the bending moment of the tower bottom is reduced; the shear of the tower bottom increases.